This invention relates to a process for making an elastically stretchable composite sheet having a comfortable touch.
Japanese Patent Application Publication No. 1994-184897A describes composite a stretchable material comprising a stretchable sheet and a necked material bonded to the stretchable sheet at three or more non-linearly arranged spots wherein the necked material is gathered between at least two of the three spots. Such a composite stretchable material can be obtained by bonding the necked material to the stretchable sheet under a stretched condition and then contracting the stretchable sheet from the stretched condition. According to this technique of prior art, the necked material changes a rubber-like surface popular in a stretchable sheet to a comfortable cloth-like surface without damaging a desired stretchability of the stretchable sheet.
According to this technique of prior art, the material previously necked by stretching it in one direction is bonded to the stretchable sheet. Consequently, the gathers are apt to distribute unevenly in a transverse direction orthogonal to the one direction at the stage that stretchable sheet is contracted from the stretched condition and thereupon the necked material is gathered. This is for the reason that, when the necked material is fibrous, the fibers lying along the side edges extending in the one direction are stretched at a ratio higher than the fibers lying intermediate regions between the side edges.
It is an object of this invention to provide a process for making an elastically stretchable composite sheet by stretching a stretchable composite web comprising an elastically stretchable web and an inelastically stretchable web so that the inelastically stretchable web may form gathers evenly distributed in the stretching direction as well as in the direction orthogonal thereto.
The object set forth above is achieved, according to this invention, by a process for making an elastically stretchable composite sheet, which can be more easily stretched than a composite web comprising an elastically stretchable web having upper and lower surfaces and an inelastically stretchable web of continuous fibers bonded to at least the upper surface of said surfaces of the elastically stretchable web, through steps of stretching the composite web in one direction and then contracting the composite web under an elastic contractible force provided by the elastically stretchable web. And the process utilizes spots to bond the elastically and inelastically stretchable webs to each other are formed in the composite web intermittently at least in the one direction of the one direction and a direction orthogonal thereto and the composite web is succeedingly stretched and then contracted in the one direction wherein a first spot of the spots and a second spot lying in the vicinity of the first spot in the one direction at least partially overlap each other as one of these first and second spots is translated in the one direction.